Buggy code:
public class BaseWicketTester extends MockWebApplication { private static final Logger log = LoggerFactory . getLogger ( BaseWicketTester . class ) ; public static class DummyWebApplication extends WebApplication { public Class getHomePage ( ) { } } public BaseWicketTester ( ) { } public BaseWicketTester ( final Class homePage ) { } public BaseWicketTester ( final WebApplication application ) { } public BaseWicketTester ( final WebApplication application , final String path ) { } public final Page startPage ( final ITestPageSource testPageSource ) { } public void executeListener ( Component component ) { } public void executeBehavior ( final AbstractAjaxBehavior behavior ) { setupRequestAndResponse ( ) ; WebRequestCycle cycle = createRequestCycle ( ) ; <START_BUG> getServletRequest ( ) . setRequestToRedirectString ( behavior . getCallbackUrl ( false , false ) . toString ( ) ) ; <END_BUG> processRequestCycle ( cycle ) ; } public final Page startPage ( final Page page ) { } public final Page startPage ( Class pageClass ) { } public final Panel startPanel ( final TestPanelSource testPanelSource ) { } public final Panel startPanel ( final Class panelClass ) { } private RuntimeException convertoUnexpect ( Exception e ) { } public Component getComponentFromLastRenderedPage ( String path ) { } public Result hasLabel ( String path , String expectedLabelText ) { } public Result isPageLink ( String path , Class expectedPageClass ) { } public Result isComponent ( String path , Class expectedComponentClass ) { } public Result isVisible ( String path ) { } public Result isInvisible ( String path ) { } public Result ifContains ( String pattern ) { } public void assertListView ( String path , List expectedList ) { } public void clickLink ( String path ) { } public void clickLink ( String path , boolean isAjax ) { } public void submitForm ( String path ) { } public void setParameterForNextRequest ( String componentPath , Object value ) { } public Result isRenderedPage ( Class expectedRenderedPageClass ) { } public void assertResultPage ( final Class pageClass , final String filename ) throws Exception { } public Result isResultPage ( final String expectedDocument ) throws Exception { } public Result hasNoErrorMessage ( ) { } public Result hasNoInfoMessage ( ) { } public void assertErrorMessages ( String [ ] expectedErrorMessages ) { } public void assertInfoMessages ( String [ ] expectedInfoMessages ) { } public List getMessages ( final int level ) { } public void dumpPage ( ) { } public void debugComponentTrees ( ) { } public void debugComponentTrees ( String filter ) { } public Result isComponentOnAjaxResponse ( Component component ) { } public void executeAjaxEvent ( String componentPath , String event ) { } public void executeAjaxEvent ( Component component , String event ) { } public TagTester getTagByWicketId ( String wicketId ) { } public TagTester getTagById ( String id ) { } private void submitAjaxFormSubmitBehavior ( AjaxFormSubmitBehavior behavior ) { } private Result isTrue ( String message , boolean condition ) { } private Result isEqual ( Object expected , Object actual ) { } private void notNull ( String message , Object object ) { } private Result isNull ( String message , Object object ) { } private void fail ( String message ) { } private void fail ( String message , Throwable t ) { } }

Fix:
getServletRequest ( ) . setRequestToRedirectString ( behavior . getCallbackUrl ( false ) . toString ( ) ) ;